i am a beginner in gardening and just planned to grow some vegetables on my terrace in grow bags. the problem here in india is that perlite/vermiculite is too expensive therefore im worried i may not be able to include that as an ingredient in the potting mixture. would coco coir, compost and red soil in the ratio 2:1:1 do fine? because i heard some amount of red soil is necessary to hold the weight of the plant when it gets big in size. or should i fill 50% of grow bag with coco peat, 25% of compost and the rest 25% with soil. please help